Method and apparatus for treating sugar beet chips

ABSTRACT

A STREAM OF SUGAR BEET CHIPS IS ADVANCED FROM ONE END TOWARDS THE OTHER END OF A SUBSTANTIALLY HORIZONTAL ENCLOSED VESSEL. AIR ENTRAPPED IN THE STREAM IS WITHDRAWN BEFORE IT ENTERS THE VESSEL. A STREAM OF SUGER BEET JUICE AT ELEVATED TEMPERATURE IS ADVANCED THROUGH THE VESSEL IN COUNTERFLOW TO THE STREAM OF CHIPS TO THEREBY PRODUCE IN THE REGION OF THE UPSTREAM END OF THE VESSEL A COUNTERFLOW ZONE. INTERMEDIATE THIS COUNTERFLOW ZONE AND THE DOWNSTREAM END OF THE VESSEL CHIPS AND JUICE ARE CONTINUOUSLY WITHDRAWN AND READMITTED INTO THE TWO STREAMS TO THEREBY PRODUCE A CORSS-CURRENT FLOW THEREIN. IN THE SAME REGION ADDITIONAL SUGAR BEET JUICE ALSO AT ELEVATED TEMPERATURE IS ADMITTED IN CROSS-CURRENT FLOW. IN THE REGION OF THE DOWNSTREAM END OF THE VESSEL THE TREATED CHIPS, TOGETHER WITH SOME OF THE INCOMING SUGAR BEET JUICE, ARE WITHDRAWN IN FORM OF A PUMPABLE MIXTURE OR SLURRY.

July 27, 1971 E L E ETAL 3,595,695

Ululfil (HIPS METHOD AND APPARATUS FOR TREATING SUGAR S Shoots-Sheet .1.

Filed Duo.

July 27, 1971 LANGEN ETAL 3,595,695

METHOD AND APPARATUS FOR TREATING SUGAR BEET CHIPS FIGS INVENTORS July 27, 1971 LANGEN ET AL 3,595,695

METHOD AND APPARATUS 1-"01'! TREATING SUGAR BEET CkillS Filed Dec. 4. 1969 5 Sheets-$heet 3 INVENTORS Haw/m MK F July 27, 1971 LANGEN ETAL METHOD AND APPARATUS FOR TREATING SUGAR BEET CHIPS 5 Sheets-Sheet 4 Filed Dec.

mm p V w 5.. T W... N iiNN W Q v v I W mls'ruou AND APPARATUS FOR TREATING SUGAR mam cums July 27, 1971 LANGEN ETAL 5 Sheets-Sheet 5 Filed Dec. 4,

INVENTORS United States Patent 3,595,695 METHOD AND APPARATUS FOR TREATING SUGAR BEET CHIPS Eugen Langen and Heinrich Weddecke, Grevenbroich, Germany, assignors to Maschinenfabrik Buckau R. Wolf Aktiengesellschaft, Grevenbroich, Germany Filed Dec. 4, 1969, Ser. No. 882,099 Claims priority, application Germany, Dec. 5, 1969, P 18 12 953.8 Int. Cl. 301d 11/02, 19/02; C13d 1/12 US. Cl. 127-5 22 Claims ABSTRACT OF THE DISCLOSURE A stream of sugar beet chips is advanced from one end towards the other end of a substantially horizontal enclosed vessel. Air entrapped in the stream is withdrawn before it enters the vessel. A stream of sugar beet juice at elevated temperature is advanced through the vessel in counterflow to the stream of chips to thereby produce in the region of the upstream end of the vessel a counterflow zone. Intermediate this counterflow zone and the downstream end of the vessel chips and juice are continuously withdrawn and readmitted into the two streams to thereby produce a cross-current flow therein. In the same region additional sugar beet juice also at elevated temperature is admitted in cross-current flow. In the region of the downstream end of the vessel the treated chips, together with some of the incoming sugar beet juice, are withdrawn in form of a pumpable mixture or slurry.

BACKGROUND OF THE INVENTION The present invention relates generally to the treating of sugar beet chips, and more particularly to a pretreatment of such chips preliminary to the subsequent sugar extraction. Still more specifically the present invention relates to a method of efiecting such treatment, and to an apparatus for carrying out the method.

As in other industries, requirements for operational efficiency are constantly becoming more demanding in the sugar beet processing industry. Particularly, it is required that the quantities of sugar lost during the processing be reduced, that the thermal energy requirements be decreased and that sugar beet processing be carried out with the aid of lesser quantities of auxiliary materials, such as formalin, anti-froth oil and the like. Detailed tests conducted with these requirements in mind have shown that optimum results can be achieved in sugar beet processing it the sugar beet chips are subjected to a particularly careful pretreatment, the so-called scalding treatment. During this scalding or pretreatment the sugar beet chips are to be plasmolyzed and, depending upon the extraction apparatus used, the mixture of chips and sugar beet juice is to be made pumpable, that is to be converted into a pumpable slurry. Plasmolysis, as is Well known, refers to the contraction or shrinking of the cytoplasm in a living cell, due to the loss of water by exosmosis.

In order to obtain improved cells during this pretreamtent it is already known to utilize a separate device for heat exchange between sugar beet chips and sugar beet juice wherein a vessel is arranged upstream of a mash apparatus, through which vessel juice and chips are passed in counterflow i.e. countercurrent flow in analogy to the subsequent movements in the extraction tower. This achieves a good heat exchange and the raw juice may be withdrawn over the screens provided, at temperatures which are only approximately -15" C. above the temperature of the incoming chips. This means that, if for "ice reasons of heat economy such an approach is desired, raw-juice temperatures of approximately 20-25 C. are obtainable so that but little heat need be supplied via the circulating juice.

It is also known in the art to supply the scalding fluid to the beet chips in counter-cross-current, with the beet chips being supplied to the vessel by the flotation method. Because of the relationship of juice used for the flotation of the chips, with reference to the chips, an average temperature of the mix is obtained in this method which can never be lower than 40 C. even if it is assumed that the original temperature of the incoming chips is at approximately 10 C. This is evidently a disadvantage. An additional disadvantage of this method resides in the fact that the incoming mixture has a rather high content of entrapped air. The undesirably high content of air is found particularly in the inlet region of the vessel. Furthermore, with this method the removal or Washingoff of surface bacteria is inadequate.

According to an additional method known in the art the beet chips are supplied to the pretreating vessel via a conduit which is oriented vertically with reference to the pretreating vessel. The purpose of this arrangement is to supply the chips in a relatively high column, thereby forcing them to sink and become immersed more rapidly in the contents of the pretreating vessel. However, air entrapped among the incoming chips can escape only very inadequately in upward direction through the tall chip column, which is a disadvantage. Furthermore, in order to assure that the column will descend steadily, that is that the lowermost chips in the column will steadily merge into the contents of the pretreating vessel, it is necessary to supply additional juice to the column. This juice, passing through the column and into the contents of the pretreating vessel, creates in the interior of the pretreating vessel in the region where the same communicates with the vertical conduit containing the column, a condition of concurrent flow which is a disadvantage becase it makes it impossible to obtain optimum heat exchange and does not provide for adequate removal of surface bacteria from the chips.

SUMMARY OF THE INVENTION It is, accordingly, an object of the present invention to provide a method of treating sugar beet chips which is not possessed of the aforementioned disadvantages.

An additional object of the invention is to provide an apparatus for carrying out the method.

In pursuance of these objects, and others which will become apparent hereafter, one feature of the invention resides in a method of treating sugar beet chips which comprises, briefly stated, the steps of advancing a stream of sugar beet chips in a predetermined enclosed path, and withdrawing entrapped air from the advancing chips in a first treating zone. A stream of sugar beet juice at elevated temperature is passed into the path at a location downstream of the first treating zone for counterflow with reference to the chips so that the latter are warmed and subjected to partial sugar extraction in a counterflow zone downstream of the first treating zone. A portion of the chips and of the juice is circulated in cross-current flow in a second treating zone downstream of the counterflow zone and additional sugar beet juice at elevated temperature is admitted in cross-current flow into said second treating zone for further raising the temperature of the chips to effect plasmolyzing and degassing of the same. The thus-treated chips are then advanced to the location where the stream of sugar beet juice is admitted into the path, for admixing with the incoming beet juice to thereby obtain a pumpable mixture which is then withdrawn from the path.

By resorting to the present invention the temperature of juice which is withdrawn in that region of the path where incoming sugar beet chips are admitted, is decreased to such an extent that it is at most 15 C. above the temperature of the incoming sugar beet chips, with plasmolysis being completed and with the juice circulating in the path-as well as the pumpable mixture which is to be withdrawn from the path for subsequent extractionbeing completely gas-free.

The present invention in efiect subdivides the scalding process into four main steps, namely the air-free supplying of incoming chips, prewarming of the chips in counterflow with the juice, plasmolyzing of the chips for simultaneous degassing in cross-current flow, and establishing of a pumpable slurry of chips and juice in a mash zone. This guarantees the quickest and most complete plasmolysis of the chips prior to entry thereof into the actual extraction apparatus, combined with the currently most advantageous heat exchange, that is optimum cooling of the raw juice obtained at a quantity of approximately 105- 150% in counterflow to the incoming freshly shredded cold chips, with a maximum temperature difference of C., and with simultaneous complete removal of the gases which are liberated during the scalding process. Furthermore, the establishment of a separate counterflow zone in the region of the inlet for the incoming sugar beet chips provides for good washing-off of the surface bacteria adhering to the newly incoming chips. The term counterflow as used herein is, of course, synonymous with countercurrent flow.

The cold raw juice produced in accordance with the present invention provides an improved heat economy for the entire sugar-producing installation because it is now possible to use so-called waste steam at low tension that is vapor from the cooking station upstream of the condenserfor heating of the raw juice, making it possible to save between 3 and 5% fresh steam beets, depending upon existing weather conditions.

The invention further provides for passing the juice, which is removed and subsequently produces the crosscurrent flow, through a surge tank or quieting vessel which is located approximately 1 meter above the upper edge of the vessel in which the pretreatment takes place, so as to obtain removal of the gases included in the thus-withdrawn juice.

It is essential in the context of the present invention that the withdrawing of entraped air and the removal of gas take place at two separate locations. The problem here is that the viscosity of the raw juice results in the development of foam as air and/ or gas are withdrawn. It is absolutely essential for an optimum achievement of the purposes of the invention that the foam so developing be reliably and completely removed, because if allowed to remain completely or partially, the foam would prevent a proper heat exchange in the counter-flow zone. Also, of course, the gases which develop in the second treating zone downstream of the counter-flow zone, which operates at uniform temperature, must be removed to reliably avoid any corrosion within the actual extraction apparatus to which the pretreated chips are to be supplied.

It is further important according to the present invention that the counterflow treatment, during which the chips are subjected to washing or flushing for removal of adhering surface bacteria and for other purposes, be as short as possible-preferably less than 30 secondsa requirement which is assured in accordance with the present invention by supplying the incoming chips free from air and by subsequently degassing them in the second treating zone in which cross-current flow takes place.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of spe- 4 cific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a longitudinal section through an apparatus according to the present invention;

FIG. 2 is a section taken on the line 11-11 of FIG. 1;

FIG. 3 is a section taken on the line III-III of FIG. 1;

FIG. 4 is a section taken on the line IV--IV of FIG. 1;

FIG. 5 is a fragmentary, partly sectioned view on an enlarged scale of a portion of the embodiment illustrated in FIG. 1;

FIG. 6 is a somewhat diagrammatic perspective view illustrating the complete apparatus according to the present invention;

FIG. 7 is a partial view of the advancing device for advancing the sugar beet chips through the apparatus, shown on an enlarged scale;

FIG. 8 is a section taken on the line VIIIVIII of FIG. 7;

FIG. 9 is a further View of the advancing device, analogous to FIG. 7;

FIG. 10 is an end view of FIG. 9;

FIG. 11 is a section taken on the line XIXI of FIG. 10; and

FIG. 12 is a schematically illustrated developed view of FIG. 7.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing now the drawing in detail it will be seen that reference numeral 1 identifies a substantially cylindrical vessel which is closed at its opposite axial ends with the covers 2 and 3. Bearings 4 and 5 are provided in the covers 2 and 3, respectively, and support a rotatable shaft 7. Ribs 6 are provided for supporting the bearing '5, and a somewhat diagrammatically shown drive 8 is provided exteriorly adjacent the cover 2 for rotating the shaft 7 about its longitudinal axis.

Located Within the vessel 1, in the region of the cover 2 and defining a raw juice collecting chamber 10, is a screen 9 of circular configuration.

As the drawing shows in various figures, including FIGS. 7 and 9, the shaft 7 has a larger diameter in the region 22 and a smaller diameter in the region 23. Mounted for rotation with the shaft 7 in the region 22 thereof are screen cleaning members 15 which wipe over the screen 9 to remove entrapped particulate matter therefrom, as well as substantially wing-shaped mixing members 17. Interspersed between the mixing members or mixing elements 17 are interruptors 16 which are secured to the inner circumferential wall of the vessel 1. For this purpose, and as shown in FIGS. 9 and 10, there are provided stiffening sheet material members 28 and ring members 27 which surround the portion 22 of the shaft 7 with spacing. As FIG. 11 shows, the interruptors are arranged at an angle to prevent backing-up of the advancing sugar beet chips.

FIGS. 7 and 8 show that the ring-shaped elements 17 which are arranged between the interruptors 16 consist of a profiled portion 29 and a planar portion 30 with grate-like cutouts 33. The portion 29 has a streamlined cross-section reminiscent of the cross-section of an airplane wing. The upper side Si. is either planar or slightly curved and constitutes the pressure side, whereas the underside 32 is strongly convexly curved and constitutes the suction side as shown in FIG. 12. The action of the elements 17 in conjunction with the interruptors 16 in a closed vessel will be evident to those skilled in the art. It is emphasized, however, that for a detailed description reference may be had to German Pat, No. 948,320. In FIG. 8 and in FIG. 12 the direction of rotation of the shaft 7 is identified with respective arrows and from FIG. 8 it will be seen that the leading edge 34 of the elements 17 is inclined in the direction of rotation at an angle alpha.

The region or section 22 of the shaft 7, in conjunction with the elements 17 and the interruptors 16, defines a countercurrent flow zone 12. Downstream and adjacent to this zone 12 there is a cross-current flow zone 13 with additional heating by admitted juice, this zone 13 being defined in the region 23 of smaller diameter of the shaft 7. In the zone 13 there is a uniform temperature range established between substantially 6775 C. It will be seen that the portion or section 23 of the shaft 7 carries mixing arms 18 which are succeeded in axial direction by stirring arms 19 with interposed interruptors 20.

A further zone 14 is provided in the region of the cover 3, and may be considered a mash zone. Located in this zone 14 is a stirring device 21 which is fastened to the shaft 7 and which serves, in conjunction with the incoming sugar beet juice which is admitted from the non-illustrated actual extracting apparatus, to produce in the zone 14 a pumpable slurry of juice and treated or rather pretreatedbeet chips.

There is further provided a disc member 24 which is mounted on the shaft 7 for rotation therewith and is located between the cover 3 and the stirring device 21. This is shown in FIG. from where it will also be evident that the disc member 24 is associated with a ring member 25 is mounted on the inside of the cover 3. One or more inlets 35 communicate with the space surrounded by the cover 3, the ring member 25 and the disc member 24, and the juice is admitted to this space. Because of this manner of admitting the incoming juice the same passes through the annular gap 26 into the interior of the vessel and is therefore uniformly distributed as it enters the zone 14.

To supply incoming chips there is provided downstream of the juice collecting chamber a filling zone 11 which communicates with a supply conduit 36. FIG. 2 shows that the conduit 36 communicates with the upper half of the vessel 1 and extends transversely to the 1ongitudinal axis of the latter, being upwardly inclined at an angle to the horizontal. A rotary feed screw 37 is located within the supply conduit 36, and a vertical feed hopper 43 communicates with the conduit 36 for admitting fresh chips into the same. Intermediate the feed hopper 43 and the inlet opening 39 at which the conduit 36 communicates with the vessel 1, an upper wall portion of the conduit 36 is provided with a screening zone 40 in which a screen 41 is arranged in the upper wall portion, the screen being covered by a plate 42 which is arranged upwardly above into a spacing from the screen 41. In the screening zone 40 a portion of the raw sugar beet juice is supplied in cross-current flow to the incoming chips. For this purpose one or, as illustrated, two inlets 44 are provided which communicate via a conduit 46 with an outlet 45 of the collecting chamber 10, as shown in FIG. 6. The juice thus supplied to the interior of the supply conduit 36, and the juice obtained by extraction of the chips, are supplied via an outlet 60 and a conduit 61 to the conduit 63 which receives juice from the chamber 10 via the outlet 62 and conveys it via a pump 64 and the conduit 65 for further processing.

As the drawing shows, particularly FIG. 6, the chamber 10 and the zone 40 are provided with outlets 66, 67 respectively. Connected to the outlet 67 is a conduit 68 leading to the foam breaking device 53 of known construction, and a conduit 69 which is connected with the outlet 66 communicates with the conduit 68 and therefore also indirectly with the foam breaking device 53. The incoming fresh chips have air withdrawn from them in the zone 40 via the outlet 67, so that they enter the vessel 1 free of air. Because the air which is so withdrawn contains foam, the conduit 68 communicates with the foam breaking device 53.

As the drawing shows, the incoming fresh chips which have entered the vessel 1, pass through the vessel 1 towards the right-hand side in FIG. 1. They pass, therefore, first through the counter-flow zone 12 and thereupon through the cross-current flow zone 13 and are made pumpable in the mash zone 14 by the stirring device 21 and addition of the incoming juice, so that they can be forwarded by pumping to the non-illustrated extraction apparatus via the outlet 47 shown in FIGS. 1 and 5, the pump 70 and the conduits 71. The juice which is introduced through the inlet or inlets 35 (see FIG. 5) in the cover 3 is obtained from the extraction device by means of a conduit 72.

FIGS. 2 and 6 show that for producing the cross-current fiow in the zone 13 there is provided a preferably cylindrical screen 48 located in the illustrated embodiment exteriorly of the vessel 1, with a cleaning screw 51 I0- tating in the interior of the screen 48 to remove adhering contaminants therefrom. The screen 48 is accommodated by housing 57 which defines a juice chamber 58. A conduit 49 communicates with the inner side of the screen 48, that is within the operative region of the rotating cleaning screw 51, and the mixture of chips, juice and foam withdrawn from the interior of the vessel 1 is supplied in this manner into the interior of the screen 48. Therein, the screw advances the mixture of juice and chips downwardly (see FIG. 2) and returns it via a return flow conduit 15 into the vessel 1. The juice collecting in the chamber 58 is withdrawn via an outlet 73- and conducted by a conduit 74 to the foam separating device 52 of known construction, where gas removal is carried out. Via a steam conduit 75 steam is supplied to the foam separating device 52. This device, also identified as an equalizing or quieting tank, thus assures a foam separation and degassing. The separated foam is conducted via a conduit 76 to the foam breaking device 53 and the degassed juice leaves the device 52 via a conduit 77.

The device 53 is further provided with an additional steam conduit 80 and with a secondary conduit 87 communicating with the juice conduit 87, so that the foam can be more readily separated into gas and juice. The gases are vented to the atmosphere via conduits 81 and 82. In the illustrated embodiment the conduit 81 is connected with an outlet 82 in the hopper 43 so that the gases can escape to the atmosphere past the incoming chips.

The foam which enters the chamber 58 is withdrawn at the outlet 78 and passed via a conduit 79 to the conduit 76 from which it enters the foam breaking device 53. A socalled pre-degassing of cell gases from the chips-which gases are liberated only in response to elevated temperatures-is carried out through the outlet 78.

The juice which is collected in the foam breaker 53 is passed via a conduit 83 to a cross-current flow pump 84 from where it advances via a conduit 86 to a heat exchanger 59 to which heat is supplied via a heat conduit 85. The juice which is heated in the heat exchanger 59 which latter may be of known construction-is largely passed via a conduit 87 to the inlet 54 and thereby into the cross-flow current zone 13. The remaining heated juice passes for foam breaking purposes via the auxiliary conduit 87' to the foam breaking device 53.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of applications differing from the types described above.

While the invention has been illustrated and described as embodied in a device for treating of sugar beets, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art fairly constitute essential characteristics of the generic or specific aspects of this invention and,

therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claim.

We claim:

1. A method of treating sugar beet chips, comprising the steps of advancing a stream of sugar beet chips in a predetermined enclosed path; withdrawing entrapped air from the advancing chips in a first treating zone; passing a stream of sugar beet juice at elevated temperature into said path at a predetermined location downstream of said first treating zone for countercurrent flow with reference to said chips in a second treating zone, so that the chips are warmed and subjected to partial sugar extraction; circulating a portion of the chips and of said juice in crosscurrent flow in a third treating zone downstream of said second treating zone, and admitting additional juice at elevated temperature for further raising the temperature of said chips for plasmolizing and degassing of the same; advancing the thus treated chips for admixing with incoming sugar beet juice; and stirring the treated chips and incoming sugar beet juice in a fourth zone to thereby obtain a pumpable mixture.

2. A method as defined in claim 1; and further comprising the step of withdrawing sugar beet juice from said path intermediate said first treating zone, and said second treating zone.

3. A method as defined in claim 1, wherein the step of circulating comprises continuously withdrawing a portion of said chips and said juice from said path in said third treating zone, withdrawing gas carried along by the thus withdrawn portions, and continuously returning the withdrawn portions in cross-current flow into said third treating zone of said path.

4. An apparatus for treating sugar beet chips, comprising advancing means for advancing a stream of sugar beet chips in a predetermined enclosed path; first withdrawing means for withdrawing entrapped air from the advancing stream in a first zone; first circulating means for circulating a stream of sugar beet juice at elevated temperature in said enclosed path in counterflow to said stream of chips for warming the same and subjecting them to partial sugar extraction in a second zone downstream of said first zone; second circulating means for circulating a portion of said chips and juice in cross-current flow to said streams in a third zone downstream of said second zone, and for admitting additional beet juice at elevated temperature to thereby raise the temperature of the chips in said stream for plasmolizing and degassing of said chips; removal means for removing gases from the plasmolized chips; and second withdrawing means for withdrawing a pumpable slurry of chips and juice from said path in a fourth zone downstream of said third zone and in which said chips and juice are stirred to convert them into said pumpable slurry.

5. An apparatus as defined in claim 4, said advancing means comprising a closed elongated vessel having longitudinally spaced end portions, a shaft coaxially mounted in said vessel for rotation therein, and a plurality of axially spaced mixing and advancing members mounted on said shaft for rotation therewith and being interspersed with flow-interrupting elements.

6. An apparatus as defined in claim 5, wherein said shaft comprises a first shaft portion of predetermined diameter traversing said second zone, and a second shaft portion of smaller diameter axially adjacent said first shaft portion and traversing said third zone.

7. An apparatus as defined in claim 5, said vessel having an inlet for said stream of beet chips, and an outlet for treated chips axially spaced from said inlet; and where in said vessel is arranged substantially horizontally but with slight upward inclination in direction towards said outlet.

8. An apparatus as defined in claim 5, said vessel having end walls at said end portions and comprising an outlet for treated beet chips arranged in the region of one of said end portions; and further comprising an opening in the associated end wall at said one end portion, a ring member stationarily mounted on the inner side of said associated end wall and surrounding said opening, and a disc member mounted on said shaft for rotation therewith adjacent said ring member and defining with the latter an annular gap; and wherein said first circulating means communicates with said opening so that said beet juice enters through the same and passes substantially uniformly distributed through said annular gap.

9. An apparatus as defined in claim 5; and drive means for rotating said shaft at speeds of between substantially 1.5 and 3 rpm.

10. An apparatus as defined in claim 5; and further comprising trap means for trapping contaminant bodies which may be present in said additional beet juice.

11. An apparatus as defined in claim 5; further comprising a supply conduit communicating with said vessel at the upstream end portion thereof and having an axis extending transversely to the elongation of said vessel and upwardly inclined with reference to the horizontal, a rotary feed screw mounted in said supply conduit for advancing a stream of sugar beet chips through the latter and into said vessel, a substantially vertical feed hopper communicating with the interior of said supply conduit, and screen means in an upwardly directed wall portion of said supply conduit intermediate said hopper and said vessel; and wherein said first withdrawing means communicates with said supply conduit through said screen means for withdrawing through the latter the air entrapped in the advancing stream of chips.

12. An apparatus as defined in claim 11; further comprising a beet juice collecting chamber; and conduit means connecting said collecting chamber with said supply conduit in the region of said screen means for circulating beet juice from said collecting chamber in cross-current flow into said stream of chips advancing in said supply conduit.

I13. An apparatus as defined in claim 5, said vessel having an inlet for said sugar beet chips and said second zone being in the region of said inlet; juice screen means arranged at an upstream end of said second zone and said second circulating means communicating with said vessel at a downstream end of said second zone so that the latter is bounded at said downstream end by said third zone.

14. An apparatus as defined in 6121111113, wherein said vessel has a predetermined inner diameter, and wherein said shaft comprises a shaft portion traversing said second zone and having an outer diameter at least equal to onethird of said inner diameter.

15-. An apparatus as defined in claim 5, said mixing members comprising ring-shaped elements provided on said shaft in said second zone inclined in direction toward said third zone and having leading edge portions which are inclined oppositely said direction.

16. An apparatus as defined in claim 15, said ringshaped elements being of streamlined configuration and so staggered circumferentially of said shaft that the pressure zone originating with each ring-shaped element in response to rotation of said shaft merges with the suction zone originating with the respective circumferentially preceding ring-shaped element.

17. Apparatus as defined in claim 15, wherein said ring-shaped elements are associated with respective ones of said flow-interrupting elements.

18. An apparatus as defined in claim 5, said third zone having an upstream end adjacent the downstream end of said second zone; and wherein said second circulating means communicating with said third zone in the region of said upstream end thereof for screening of said portions of chips and juice.

'19. An apparatus as defined in claim 18, wherein said screen element is located exteriorly of said vessel, and wherein said second circulating means comprises outflow and inflow conduits respectively communicating with said vessel and with opposite sides of said screen element.

20. An apparatus as defined in claim 19, wherein said screen element is cylindrical, and wherein said second circulating means comprises a screw element mounted for rotation coaxially within said screen element and operative for receiving matter trapped in the interstices of the same.

21. .An apparatus as defined in claim 20; and further comprising foam separating and breaking means communicating with said screen element for removing foam carried by said portions, and breaking such foam down into its constituent liquid and gaseous phases.

22. An apparatus as defined in claim 21, wherein said foam separating and breaking means comprises a foam separating device and a discrete foam breaking device separate from said separating device.

References Cited UNITED STATES PATENTS 2,853,405 9/1958 Heinrich 12745X 5 2,857,907 10/1958 Kaether 12745X 2,928,760 3/ 1960 Christofiersen 1275X 3,313,653 4/1967 Jung 12745X 3,355,260 11/ 1967 Bruniche-Olsen 1275X 10 MORRIS O. WOLK, Primary Examiner S. MARANTZ, Assistant Examiner US. Cl. X.R. 

